@karkusha could you downgrade your bios 2 versions lower with ez flash in the bios itself, and after it succeeds, power off, and do the bios flashback again but with the new file?
This time, could you try it with thie mod bios file here instead: [Offer] Asus P9X79 BIOS Mods (NVMe Boot, ReBar, etc.)
I did a new upload (different than this one, but i forgot the key difference) because i wasn’t sure with the one i gave in this post was a good mod one. Just erase the old one you downloaded from this page.